Layer system for the formation of a surface layer on a surface of a substrate and also arc vaporization source for the manufacture of a layer system

ABSTRACT

The invention relates to a layer system for the formation of a surface layer on a surface of a substrate, in particular on the surface of a tool, wherein the layer system includes at least one first hard layer of the composition (Al a Mg b Cr c Me d B e AX m Si k ) α (N u C v O w ) β  with (a+b+c+d+e+m+k)=α, (u+v+w)=β and (α+β)=100, wherein 40 ≦α≦60 and wherein Me is at least one element of the group of the chemical elements consisting of: the secondary groups IVb, Vb and VIb of the periodic system of the chemical elements. The component AX is at least one element of the group of the chemical elements consisting of: the elements of the main group Ia and the elements Be, Ca, Sr, Ba and the elements of the secondary groups VIIb, VIIIb, Ib, IIb, IIIb and the elements of the group of the lanthanoids, of the periodic system of the elements, wherein 0.004≦m&lt;60, and preferably 0.01≦m&lt;50. In accordance with the invention 0.4≦a≦58 and 0.04≦b≦12 and 18≦c≦42.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 of EuropeanPatent Application No. 07110938.3 filed on Jun. 25, 2007, the disclosureof which is expressly incorporated by reference herein in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A COMPACT DISK APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

The invention relates to a layer system for the formation of a surfaceon a substrate, to a vaporization source for the manufacture of a layersystem and also to a substrate, in particular to a tool having a layersystem in accordance with the invention, all in accordance with thepreambles of the independent claims of the respective categories.

The manufacture of performance tools and components is mainly realizedby the coating of their surfaces. An important class of such coatedsubstrates are tools, among other things in particular chip-formingtools and also components and machine parts for machines which aresubject to wear in all possible embodiments. Typical substrate materialswhich are coated are among other things tool steels and hard metals butalso all other possible substrate materials.

A known problem in the coating of these materials is that they have arelatively high oxidation rate in air at around 500° C. and soften atrelatively low temperatures (ca. 500° C. for HSS and 650° C. for a hardmetal).

Accordingly, ceramic cutting bodies are also preferably used, forexample on the basis of cubic boron nitride for the hard machining ofsteels. Thus, the most diverse SiN ceramics are, for example, used forthe high speed machining of aluminum alloys and grey cast ion. Theceramics prove to be substantially more durable in comparison tometallic tool materials. A further increase in performance can beachieved by suitable coating of the tools.

The hard material layers known from the prior art are in this respectfrequently based on the classic compounds such as TiN, TiNC, CrN. Theseknown hard layers do however have their limits with respect to theirfield of use above all with respect to their ability to work at hightemperatures. On the one hand, the hardness drops off notably atelevated temperatures and, on the other hand, oxidation already sets inat relatively low temperatures and can lead to an increased layer wearat the temperature of use.

In order to avoid these problems essentially two layer classes have beendeveloped which have oxidation resistance in the range up to 1000° C.and also have improved characteristics with respect to the hardness.

The one layer class relates to Al containing base layers such as AlTiNand AlCrN to which additional elements can be alloyed depending on therequirement. Typical compounds from this area are compounds of the formAlTiX-NCO, wherein X is, for example, Cr or another metal.

Another route followed in the prior art for the performance increase ofcoated tools consists in the combination of classic hard material layersas a carrier layer combined with finish layers as a functional layer.The high silicon containing layers (10 at-% or more); at-% signifies inthe context of this application “atomic percent” of the type MeSiXNCOlayer (X is further metals or B) are to be named, such as TiSN whichhave a significantly improved ability to withstand the temperatureloading.

In addition it is furthermore known for example to deposit oxidicceramic layers such as Al₂O₃ by means of CVD processes on indexable orreversible cutting inserts in order to be able to counteract wearprocesses at elevated contact temperatures in particular during turning.

In addition boron based layers such for example B₄C and also cubic BNlayers are at the stage of research. However, cubic BN has the decisivedisadvantage that is extremely complicated to present. This is above alldue to difficulties of the layer growth itself but also brought about bytoo high inherent stresses in the layers.

In the field of high temperature materials bulk ceramics on the basis ofSiCN have been produced in recent years which are characterized by highhardness and an improvement of the resistance to oxidation in relationto SiC and Si₃N₄. Their special characteristics are based on the complexcovalent chemical bonds and the low diffusion rate of oxygen in theamorphous structure of SiCN.

However, despite all previous efforts, the provision of coatings hasonly partly succeeded which are able to meet increasingly higher demandson the mechanical characteristics such as for example the hardness,residual compressive stress and toughness, tribological characteristicssuch as tendency to adhesion at higher temperatures and also friction,the oxidation resistance, phase stability and other characteristicproperties, above all also at extreme temperatures.

Moreover, the above-described higher performance layers can also only bemanufactured with great difficulties from the technical method viewpoint and the tools coated therewith are very expensive, so that,however, when considered from the point of view economy, coating is inmany cases not worth while or such coated tools only have a restrictedmarket.

BRIEF SUMMARY OF THE INVENTION

An object of the invention is to make available improved coatings for asubstrate, in particular for a tool or a part subjected to wear whichovercomes the problems known from the prior art and has in particular atribologically positively acting oxidation behavior and phase stability,improved mechanical properties, above all but not only with respect tothe hardness and the residual compressive stress is and which can alsobe used under extreme temperature conditions.

Another object of the invention is to make available a vaporizationsource with which the new improved hard layers can be manufactured.

A layer system for the formation of a surface layer on a surface of asubstrate, comprising: at least one first layer having the composition(Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k))_(α)(N_(u)C_(v)O_(w))_(β)with (a+b+c+d+e+m+k)=α, (u+v+w)=β and (α+β)=100, wherein 40≦a≦60 andwherein Me is at least one metal of the group of the chemical elementsconsisting of: the elements of the secondary groups IVb, Vb, VIb of theperiodic system of elements; wherein AX is at least one element of thegroup of the chemical elements consisting of: the elements of the maingroup IA, the elements Be, Ca, Sr and Ba, the elements of the secondarygroups VIIb, VIIIb, Ib, IIb and IIIb, and the elements of the group ofthe lanthanoids of the periodic system of chemical elements; wherein0.004≦m<60, 0.4≦a≦58, 0.04≦b≦12 and 18≦c≦42. Additionally, in oneembodiment, 0.01≦m<50.

In another embodiment, at least one of 20≦a≦42, 0.02≦b≦6, Me is presentin a quantity corresponding to 4≦d≦54 in the hard layer, and Si ispresent in a quantity of at most k=24 in the hard layer.

In another embodiment, AX is at least one of Li, Be, Ca and Si. Inanother embodiment, AX is at least one of Sc, Y and La. In still anotherembodiment, AX is at least one element of the group of the lanthanoids.In still another embodiment, AX is a mixed metal.

In another embodiment, the layer system includes at least one additionalsecond layer of the composition(M_(o)Si_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))δ with (o+p+q)=γ, (r+s+t)=δ, and(γ+δ)=100, wherein 40≦γ≦60 and wherein M is at least one metal of thegroup of the chemical elements consisting of: Al and the elements of thesecondary groups IVb, Vb, VIb of the periodic system of elements,wherein AY is at least one element of the group of the chemical elementsconsisting of: Mn, Fe, Co, Ni, Cu, the elements of the secondary groupIIIB, the elements of the main group IA, IIA and IIIA and the elementsof the group of the lanthanoids of the periodic system of chemicalelements.

In another embodiment, AY further contains boron. In still anotherembodiment, AY is an element of the group of the chemical elementsconsisting of Y and the lanthanoids. In another embodiment, AY is anelement of the group of the chemical elements consisting of Y and atleast one of Ce and La.

In another embodiment, at least one of 0.04≦p≦30, 0.004≦q≦6, and0.01≦q≦10.

In another embodiment, the first hard layer is a terminal cover layer ofthe layer system. In still another embodiment, the second hard layer isa terminal cover layer of the layer system.

In another embodiment, the layer system further comprises a functionallayer, and the functional layer is a composite layer, and the functionallayer is on a surface of the substrate.

In another embodiment, the functional layer is a composite layer ofMet_(x)E_(y)N_(z), with x>0; y≧0 and z>0, wherein Met is at least onemetal of the group Al, Cr, Mo, W, V, Nb, Ta, Ti, Zr, HF, Mn, Fe; Co, Ni,Li, Be, Mg, Sc, Y, La, Ce, Nd, Sm; and wherein E is an element of thegroup Si, B, C, O.

In still another embodiment, the layer system further comprises at leastone of an intermediate layer and a gradient mixed layer, wherein anintermediate layer comprises at least one of Si and C, and wherein thegradient mixed layer comprises the at least one of Si and C of theintermediate layer, the composition(Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k))_(α)(N_(u)C_(v)O_(w))_(β) ofthe first layer, and the composition(M_(o)Si_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))_(δ) of the second layer.

An arc vaporization source having a vaporization material as cathode forthe generation of a surface layer on a surface of a substrate byvaporization of the vapor material by means of an arc discharge on avaporization surface of the cathode, wherein the vaporization materialhas a chemical composition(Al_(a′)Mg_(b′)Cr_(c′)Me_(d′)B_(e′)AX_(m′)Si_(k′)) with(a′+b′+c′+d′+e′+m′+k′)=100, wherein Me is at least one element of thegroup of the chemical elements consisting of the secondary groups IVb,Vb and VIb of the periodic system of the chemical elements, and whereinAX is at least one element of the group of the chemical elementsconsisting of the elements of the main group Ia, the elements Be, Ca,Sr, Ba, the elements of the secondary groups VIIb, VIIIb, Ib, IIb, IIIband the elements of the group of the lanthanoids of the periodic systemof the chemical elements, wherein 0.01≦m′<100, wherein 1≦a′≦97,0.1≦b′≦20 and 30≦c′≦70.

In another embodiment, the vaporization material further comprises atleast one of C, N and O.

In another embodiment, AX is at least one of Li, Be, Ca and Si, orwherein AX is at least one of Sc, Y and La, or wherein AX is at leastone element of the group of the lanthanoids, or wherein AX is a mixedmetal.

An arc vaporization source having a vaporization material as a cathodefor the generation of a surface layer on a surface of a substrate byvaporization of the vaporization material by means of an arc dischargeon a vaporization surface of the cathode, wherein the vaporizationmaterial has a chemical composition (M_(o′)Si_(p′)AY_(q′)) with(o′+p′+q′)=100, and wherein M is at least one metal of the group of thechemical elements consisting of Al and the elements of the secondarygroups IVb, Vb, VIb of the periodic system of the elements and whereinAY is at least one element of the group of the chemical elementsconsisting of Mn, Fe, Co, Ni, Cu, the elements of the secondary groupIIIB, the elements of the main group IA, IIA and IIIA and the elementsof the group of the lanthanoids of the period system of the chemicalelements.

In another embodiment, a substrate coated with a layer system, whereinthe substrate is at least one of an original tool, a master tool, amould, a press tool, a chip forming tool, a drill, a milling cutter, anindexable cutting insert, a planing tool, a reshaping tool, amicro-tool, a micro drill, a micro indexable cutting insert, a micromiller, a plastic tool, and a substrate of a part; wherein the substrateis a part subjected to wear from at least one of an air-based turbine, aland-based turbine, a motor, a combustion engine, a seal, a gear, apiston, a piston ring, a part subjected to wear in a textile machine,and a part generally subjected to wear.

BRIEF DESCRIPTION OF THE DRAWINGS

Not Applicable

DETAILED DESCRIPTION OF THE INVENTION

The invention thus relates to a layer system for the formation of asurface layer on a surface of a substrate, in particular on the surfaceof a tool, wherein the layer system includes at least one first hardlayer of the composition(Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k))_(α)(N_(u)C_(v)O_(w))_(β)with (a+b+c+d+e+m+k)=α, (u+v+w)=β, and (α+β)=100, wherein 40≦a≦60 andwherein Me is at least one element of the group of the chemical elementsconsisting of the secondary groups IVb, Vb and VIb of the periodicsystem of the chemical elements. The component AX is at least oneelement of the group of the chemical elements consisting of the elementsof the main group Ia, the elements Be, Ca, Sr and Ba. The elements ofthe secondary groups VIIb, VIIIb, Ib, IIb, IIIb and the elements of thegroup of the lanthanoids, of the periodic system of the elements wherein0.004≦m<60, and preferably 0.01≦m<50. In accordance with the invention0.4≦a≦58 and 0.04≦b≦12 and 18≦c≦42.

This formulation is equivalent to saying that the layer system is forthe formation of a surface layer on a surface of a substrate, inparticular on the surface of a tool with the layer system having atleast one hard layer of the composition(Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)A_(m)Si_(k))G with a (a+b+c+d+e+m+k)=100and G being at least one element of the group of the chemical elementsconsisting of N, C and O. Me is at least one element from the group ofthe chemical elements consisting of the secondary groups IVb, Vb and VIbof the periodic system of the chemical elements and A is at least oneelement of the group of chemical elements consisting of the elements ofthe main groups Ia, IIa and the elements of the secondary groups VIIb,VIIIb, Ib, IIb, IIIb and the elements of the group of the lanthanoids ofthe periodic system of elements, with 0.01≦m<100. In accordance with theinvention 1≦a≦97 and 0.1≦b≦20 and 30≦c≦70. In this formulation the sum(a+b+c+d+e+m+k) is related 100 and not as in claim 1 of the presentapplication to α. Although the formulation (a+b+c+d+e+m+k)=100 isessentially identical to (a+b+c+d+e+m+k)=α, insofar as the group G isnot specified more closely, (a+b+c+d+e+m+k)=100 can, in cases of doubt,lead to a lack of clarity so that in the following the clearerformulation (a+b+c+d+e+m+k)=α will be used.

For the sake of better distinction the symbol AX will moreover be usedin place of the symbol A for the component A in the formula unit(Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)A_(m)Si_(k)).

The considerably improved performance of the tools and components incomparison to the prior art is thus achieved in accordance with theinvention in that the corresponding substrates are coated with a hardlayer of the composition (Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k))G,with G being a composition known per se of at least one element of thegroup of nitrogen (N), carbon (C) and oxygen (O) and thus for examplestanding for (N_(u)C_(v)O_(w))_(β) and Me is at least one metal of thegroup of the chemical elements consisting of the elements from thesecondary groups IVb, Vb, VIb of the periodic system of elements and Ais at least one element of the group of the chemical elements consistingof the elements of the main groups Ia, IIa, and the elements of thesecondary groups VIIb, VIIIb, Ib, IIb, IIIb, and the elements of thegroups of the lanthanoids of the periodic system of elements.

The significantly improved characteristics of the layer systems of theinvention, above all with respect to hardness, residual compressivestresses, resistance to oxidation and phase stability at thetemperatures up to 1200° C. and more could be achieved in that, inaccordance with the invention, the proportion of aluminum (Al) isrestricted 0.4≦a≦58 and at the same time the proportion of magnesium(Mg) is restricted to 0.04≦b≦12 and the proportion of chrome (Cr) to18≦c≦42.

The secondary groups IVb, Vb, VIb, from which the metal Me can beselected consists of the elements titanium (Ti), zirconium (Zr), hafnium(Hf) of the group IVb, of the elements vanadium (V), niobium (Nb),tantalum (Ta) of the group Vb and of chrome (Cr), molybdenum (Mo) andtungsten (W) of the secondary group VIb of the period system ofelements.

The main groups Ia and IIa of the periodic system of elements from whichthe formula AX can be selected in a known manner from the elementshydrogen (H), lithium (Li), sodium (Na), potassium (K), rubidium (Rb),caesium (Cs) and francium (Fr) of the main group Ia and of the elementsberyllium (Be), magnesium (Mg) calcium (Ca), strontium (Sr), barium (Ba)and radium (Ra) of the Group IIa.

The secondary group Ib consists of the chemical elements copper (Cu),silver (Ag), Gold (Au) and terbium (Tb), the secondary group IIbconsists of the chemical elements zinc (Zn), cadmium (Cd), mercury (Hg)and dysprosium (Dy), whereas the secondary group IIIb consists of thechemical elements scandium (Sc), yttrium (Y), lanthanum (La) andactinium (Ac).

The further secondary groups VIIb and VIIIb from which the component AXof the formula unit (Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k)) canlikewise be selected, consists of the chemical elements manganese (Mn),technetium (Tc), rhenium (Re) of the secondary group VIIb and iron (Fe),ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir),nickel (Ni), palladium (Pd) and platinum (Pt) of the secondary groupVIIIb of the periodic system of chemical elements.

In known manner the chemical elements cerium (Ce), praseodymium (Pr),neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu),gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium(Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu) belong to the groupof the lanthanoids.

It has now been shown in a surprising manner that the hard layers knownfrom the prior art which have the initially mentioned disadvantages suchas in particular lack of resistance to oxidation and lack of phasestability, above all at higher temperatures, such as are for examplevery frequently to be encountered with high performance tools in theoperating state, can be decisively improved by the above quotedrestricted of the content of aluminum, magnesium and chromium in thecompound of the invention (Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k))G.By suitable choice of the chemical compositions through the presentinvention one has for the first time succeeded in simultaneouslyoptimizing the resistance to oxidation, the phase durability, hardness,residual compressive stress and other decisive parameters such as forexample the bond strength in a(Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k))G layer.

In this connection, and thus unless otherwise expressly mentioned, thestatements of quantity indicated in the context of this application byindices at the chemical elements or at the symbols representing thechemical elements are to be understood throughout as atomic-% (at-%).That is to say that, for example, the statement 0.01≦m<100 with(a+b+c+d+e+m+k)=100 signifies that the components A_(m) in the formulaunit (Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k)) is present in an amountbetween 1 at-% and 50 at-%.

It has in particular been shown that the layers of the layer system ofthe invention can also advantageously be combined with already knownlayers in the layer system to form new layer systems so that completelynew layer systems can be made available by the present invention incomparison to the prior art which have characteristics in comparison tothe prior art which have been improved in almost every respect.

Thus, in a layer system in accordance with the invention differentlayers which can have quite different functions can be excellentlycombined in a layer system in accordance with the invention with a firsthard layer without for example problems arising with the bond strengthbetween the layers or on the substrate and without the layer system inaccordance with the invention deteriorating in the course of time, forexample by undesired diffusion processes or other physical chemicalreactions or failing at high temperatures and large mechanical loadingsin the operating state. The conventional layer known from the prior artsuch as for example layers of the classical compounds such as TiN, TiNC,CrN and others are also able to be combined advantageously with a firsthard layer in accordance with the invention depending on therequirements.

The part layers of a first hard layer with the chemical composition(Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k))G of a layer system inaccordance with the invention can also take on the most diversefunctions by a suitable specific choice of the content of Al, Mg andchromium. Thus, an (Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k))G layer inaccordance with the invention can in one case be a bond layer whichproduces an excellent bond of the total layer system to the substrate inthat it for example matches the grid parameters of the substrate to thefurther layer system or in that the special chemistry of the substrateis matched to that of the further layer system.

An (Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k))G layer in accordance withthe invention can however also form an intermediate layer with thefunctions known per se, for example in a modified chemical compositionin a layer system or, however, also be a covering first hard layer whichprotects the substrate, for example a tool or part subjected to wearagainst thermal, mechanical and chemical attacks.

In an example important in practice the component AX is a mixed metal.

The use of at least one rare earth element has proved advantageous asthe component AX for the formation of a mixed metal. The group of therare earth elements includes in this respect in known manner thelanthanoids and also lanthanum, scandium and yttrium. In this connectionthe pure elements of the group of the rare earths are indeed entirelydifferent with respect to specific characteristics, for example withrespect to the melting and vaporization points, the vapor pressure etc.,however these elements are if any thing very similar rather thandifferent with respect to their chemical properties and this alreadymanifests itself in the fact that their separation causes greatdifficulties in practice.

Thus, the rare earths are frequently also used in the form of the saidmixed metals, i.e. it is not pure metals of the group of the rare earthsthat are used for alloying processes for example, but rather specificmixtures which contain two or more elements of the group of the rareearths and possibly also further different chemical elements inpredeterminable quantities. In this connection it is known that theaddition of very small quantities of mixed metals can massivelyinfluence the chemical and physical characteristics of a basic substancedepending on the composition.

It has in this respect been shown that the use of mixed metals as acomponent of the chemical component AX can lead to a situation in whicheven the smallest quantities of mixed metals can enormously influencethe desired characteristics of a layer system in accordance with theinvention without corresponding serious changes having to be toleratedfor example in the chemical properties or in the lattice structure. Inthis connection the definition of the “mixed metal” is not absolutelyunambiguous in the literature. In the context of the present applicationthe term “mixed metal” will however be understood with a very broadtechnical significance.

In a very narrow definition, which is simply used as a specific examplefor specific mixed metal, and which in no way restricts the significanceof the term “mixed metal” for the present application, a mixed metal,also a cerium mixed metal, is a metal alloy of metals of the rareearths. It consists for example to 45% to 52% of cerium, to 20% to 27%of lanthanum, to 15% to 18% of neodymium, to 3% to 5% of praseodymiumand to 1% to 3% of samarium, terbium and yttrium, traces of other rareearth metals, calcium and silicon and up to 5% of iron. The compositioncan for example result directly from the starting mineral monazite. Ifthe proportion of iron exceeds 15% (mainly up to 50%) one frequentlyalso speaks of cerium iron.

As a result of the similarity of the chemical properties of the rareearths deviations in the composition are uncritical for specificproperties whereas other properties can indeed be really influenced by achange of the chemical composition.

Mixed metals can reduce unwanted iron oxides as an additive during themanufacture of steel, they can bind oxygen and sulphur and assist thedegassing. As alloying metals they can help improve the casting and flowproperties and also the corrosion resistance of iron-chrome-aluminummaterials in hot oxidizing gases.

The following Table 1 shows five special examples of mixed metals, withthe definition of the term “mixed metal” being significantly stretchedfor the examples of the Table 1. Thus the mixed metals of the Table 1include, in addition to different rare earths also other additives andindeed both metals and also non-metals such as Fe, Si, Mg, S andphosphorus. Other elements such as hafnium (Hf), cobalt (Co), zirconium(Zr), nickel (Ni) and further elements of the periodic system can alsobe present in a mixed metal.

However, as already mentioned, the Table 1 is only to be understood asan example for the significance of the term “mixed metal” in the contextof this application and in no way acts restrictively for the class ofthe very different mixed metals which can be advantageously included bythe component AX in a layer system in accordance with the invention.

TABLE 1 Mixed metal 1 Mixed metal 2 Mixed metal 3 Mixed metal 4 Mixedmetal 5 La 25-33% 25-34% 25-34% 30-40% 44-50% Ce 48% min. 48-55% 48-55%60-70% 50-56% Pr  4-7%  4-6%  4-6% 0.5% max. 0.1% max. Nd 11-15% 14-17%14-17% 0.5% max. 0.1% max. Fe 0.5% max.  0.2% max. 0.5% max. 0.5% max.0.5% max. Si 0.2% max. 0.05% max. 0.2% max. 0.2% max. 0.2% max. Mg 0.5%max. 0.05% max. 0.5% max. 0.5% max. 0.5% max. S 0.02% max.  0.02% max.0.02% max.  0.02% max.  0.02% max.  P 0.01% max.  0.01% max. 0.01% max. 0.01% max.  0.01% max. 

The proportion of aluminum (Al) is advantageously selected to lie in therage 20≦a≦42 and the proportion of magnesium (Mg) in the range from0.02≦b≦6. It has in particular being shown that the choice of theproportion of La and Mg in the named range leads to a good compromise inthe optimization of the resistance to oxidization and phase durabilitywith a simultaneous increase of the hardness, residual compressivestress and toughness of the layers, with it also being possible toachieve good tribological properties in addition.

The metals Me of the secondary groups IVb and/or Vb and/or VIb arepreferably present in a quantity corresponding to 4≦d≦54 in a first hardlayer. Through this choice of the composition a further increase of thehardness can be achieved in comparison to the hard layers known from theprior art, with it being possible to achieve optimization of the nitrideformation by a suitable choice of the specific composition of the metalgroup Me depending on the use of the layer.

In a special case Si is present in a quantity of at most k=24 in thefirst hard layer. Whereas nitrogen (N) contributes among other thingssubstantially to the hardness of the layer system and silicon (Si) isimportant for the resistance to oxidation, the additional use of boron(B) leads to the resistance of the structure to thermal loadings beingsignificantly improved.

Through the setting of the silicon content to the named range it is forexample possible to simultaneously further optimize the resistance tooxidation and the toughness and/or hardness of the layer within specificlimits, but not only these and/or in addition to other measures.

In very special cases, when (for example) for specific reasons thechemical elements which form a component AX tend to have a smalleratomic diameter or when specific chemical boundary conditions are to besatisfied, the component AX can be formed exclusively only of Li and/orof Be and/or of Ca and/or of Si.

In this connection, further special cases are possible for similar orother reasons. Thus AX can in another case also only be Sc and/or only Yand/or only La, or AX can be only at least one element of the group ofthe lanthanoids, in particular only Ce and otherwise include no otherelement.

In the following some exemplary embodiments of layer systems inaccordance with the invention will be discussed which were firstmanufactured for the sake of simplicity as one layer systems of thefirst hard layer for the determination of the specific layer parameters.It will be understood that not only the following layer systems butrather in particular also all examples presented in the context of thisapplication can also be advantageously combined.

In one embodiment an AlCrMgSiN layer was investigated.

This first hard layer was applied in a manner known per se by means ofan arc vaporization source in a corresponding process chamber which islikewise known to the person skilled in the art. One used arcvaporization source, often only simply termed a cathode, has a diameterof 100 mm and the following chemical composition apart from technicallyunimportant contaminants: 68 at-% Al, 29.5 at-% Cr, 1.5% at-% Mg and 1at-% Si.

The composition of the applied layer was then determined in thefollowing manner:

REM: LEO, EDX: INCA, acceleration voltage 15 keV.

This investigation resulted in the following composition of the layerapplied to the substrate: 64.03 at-% Al, 33.93 at-% Cr, 1.08 at-% Si and0.96 at-% Mg.

For the coating, a substrate, in the present case a high speed steel,was first heated in the process chamber to circa 500° C. subjected toion cleaning and subsequently coated in pulsed manner at a gas pressureof approximately 6.5 Pa at a cathode current of ca. 150 Amps and with abias voltage of ca. 50 V.

For the comparison an AlTiN layer known from the prior art wasmanufactured, with a cathode being used having 55 atomic-% Al and 45Atom-% Ti.

The required nitrogen was made available for both layers via the processgas in the process chamber.

The following Table 2 compares the most important layer properties ofthe two so produced layers.

TABLE 2 AlTiN AlCrMgSiN Micro-hardness Knoop 2500 2850 [HK0.025] Wearrate 2.9 1.9 [m²/(Nm)] Surface resistance [Ohm] 10 27.250

The micro-hardness in accordance with Table 2 was in this connectiondetermined in known manner in accordance with the method of Knoop andthe wear rate was measured via the abrasion resistance with a KALOTESTwith kalo-MAX NT of the company BAQ with a ball diameter of 30 mm and540 shaft rotations at 60 rpm using a grinding emulsion. The surfaceresistance was measured with a multimeter with a spacing between themeasuring tips of ca. 10 mm.

Table 2 demonstrates a significantly greater hardness and a wear ratereduced by circa one third for the AlCrMgSiN layer of the invention incomparison to the known AlTiN layer of the prior art. The enormouslyhigh surface resistance of the AlCrMgSiN layer of the invention isnotable and is approximately 3000 times larger than that of the knownAlTiN layer. This makes the layer of the invention particularlyinteresting, above all for fields of use in which the flow of surfacecurrents must be prevented or reduced or the creation of magnetic andelectric fields as a result of surface currents must be suppressed orprevented. Thus the layer in accordance with the invention is inparticular also particularly well suited for applications in whichcorresponding electromagnetic and in particular dielectriccharacteristics of the layer play a role.

In a further embodiment which is very important in practice a layersystem in accordance with the invention includes at least one additionalhard layer of the composition (M_(k)Si_(l)A_(m))G with (k+l+m)=100, withG being at least one element of the group of the chemical elementsconsisting of N, C and O. In this connection M is at least one metal ofthe group of the chemical elements consisting of Al and the elements ofthe secondary groups IVb, Vb, and VIb of the periodic system of theelements. The component A of the second hard layer is at least oneelement of the group of the chemical elements consisting of Mn, Fe, Co,Ni, Cu and the elements of the secondary group IIIb and the elements ofthe main groups Ia, IIa, IIIa and the elements of the group of thelanthanoids of the periodic system of the chemical elements.

That is essentially identical with the statement that the layer systemincludes at least one additional second hard layer of the composition(M_(o)Si-_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))δ with (o+p+q)=γ, (r+s+t)=δ,and (γ+δ)=100, wherein 40≦γ≦60 and wherein M is at least one metal ofthe group of the chemical elements consisting of Al and the elements ofthe secondary groups IVb, Vb, VIb of the periodic system of elements.The component AY is at least one element of the group of the chemicalelements consisting of Mn, Fe, Co, Ni, Cu and the elements of thesecondary group IIIB and the elements of the main group IA, IIA and IIIAand the elements of the group of the lanthanoids of the periodic systemof chemical elements.

For the sake of better distinction the symbol A in the formula unit(M_(k)Si_(l)A_(m)) is replaced by the symbol AY in the formula unit(M_(o)Si_(p)AY_(q))_(γ).

A further considerably improved performance of the tools and componentsin comparison with the prior art was thus achieved in that thecorresponding substrates were coated with an additional second hardlayer of the composition (M_(k)Si_(l)A_(m))G more precisely(M_(o)Si_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))_(δ) with G thus being acomposition known per se of at least one element of the group nitrogen(N), carbon (C) and oxygen (O), i.e. G has for example the chemicalstructure (N_(r)C_(s)O_(t))_(δ) and M is at least one metal of the groupof the chemical elements consisting of aluminum (Al) and the elements ofthe secondary groups IVb, Vb, VIb of the periodic system of elements.

The characteristics of a layer system in accordance with the inventionwith a second hard layer which have been significantly improved onceagain, above all with respect to the hardness, residual compressivestresses, resistance to oxidation and phase stability up to temperaturesof 1200° C. and more could be achieved in that the component AYsupplements the chemical composition of the second hard layer, with AYbeing supplemented by at least one element of the group of the chemicalelements consisting of manganese (Mn), iron(Fe), cobalt (Co), nickel(Ni), copper (Cu) and the elements of the secondary group IIIB, theelements of the main group IA, IIA, IIIA and the elements of the groupof the lanthanoids of the periodic system of the chemical elements. Inmanner know per se the main group IIIa of the periodic system of theelements consists in this respect of the elements boron (B), aluminum(Al), gallium (Ga), indium (In) and thallium (TI).

The use of at least one rare earth element for the component AY of thesecond hard layer has proved to be particularly advantageous. In thisconnection it has been found that the addition of very small quantitiesof mixed metals can already massively influence the chemical andphysical properties of a second (M_(k)Si_(l)A_(m))G hard layer,depending on the composition.

In a surprising manner it has in addition being shown that, through theaddition of the component AY to the second hard layer in the form of oneor more rare earth elements and/or of one or more elements of the maingroup IA and/or IIA and/or IIIA these properties can be decisivelyimproved, the present invention having succeeded for the first time, bya suitable choice of the chemical compositions, in still furtherimproving and optimizing the resistance to oxidation, the phasedurability, the hardness and other decisive parameters such as forexample the bond strength and the residual compressive stresses.

In particular it has also been shown that the layers of the type of thesecond hard layer can advantageously be combined with already knownlayers and layer systems to form new layer systems so that through thepresent invention completely new layer systems can be made availablewith properties improved in almost every respect in comparison to theprior art.

This is in particular due to the fact that for a suitable choice of thechemical elements which form the component AY in the layer system(M_(k)Si_(l)A_(m))G i.e. (M_(o)Si_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))_(δ) inaccordance with the invention, the layer system of the present inventionachieves an enormous flexibility because, for example, a large selectionof atomic diameters is available for the component AY of the second hardlayer, whereby, for example, lattice parameters can be matched withoutnegatively influencing the chemical bonding possibilities.

The part layers can also include a second part layer with the chemicalcomposition (M_(o)Si_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))_(δ) of a layersystem in accordance with the invention and also take on the mostdiverse functions by a suitable choice of the chemical composition ofthe component AY. Thus a second(M_(o)Si_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))_(δ) hard layer can for examplein one case be a bond layer which produces an excellent adhesion of thetotal layer system to the substrate in that it matches for example thelattice parameter of the substrate to the further layer system, or inthat the special chemistry of the substrate is matched to that of thefurther layer system.

A second (M_(o)Si_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))_(δ) hard layer canhowever also form an intermediate layer with the functions known per sein a modified chemical composition in a layer system or, however, alsobe a covering first hard layer which protects the substrate, for examplea tool or a part subjected to wear against thermal, mechanical orchemical attacks.

In a preferred embodiment the component A of the second hard layer canadditionally contain boron (B). Whereas nitrogen (N) contributes amongstother things significantly to the hardness of the layer system andsilicon (Si) is important for the resistance to oxidation, theresistance of the structure to thermal loads can be significantlyimproved still further by the additional use of B.

It is preferable, but not necessary, for the proportion of Si in thesecond hard layer to be set to a range of 0.04≦p<30.

By the setting of the silicon content to the named range it is, forexample, possible to simultaneously optimize the oxidation resistanceand the toughness or hardness as well as the residual compressivestresses of the second hard layer, and thus of the total layer system inaccordance with the invention, within predeterminable limits or tooptimize them in addition to other measures.

The proportion of the chemical component AY in the formula unit(M_(o)Si_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))_(δ) of the second hard layerthereby preferably lies in the range 0.004<q<6 and, as alreadymentioned, the statement should naturally be understood as atomicpercent.

Through the choice of the component AY of a second hard layer in thenamed range it is possible as has been shown, to further improve thephase durability by a layer system in accordance with the invention, inaddition to further parameters, even at very high temperatures and evenabove 1200° C.; however, the oxidation resistance can also be therebyfurther increased and relevant lattice parameters can simultaneously bematched so that a desired inherent stress level of the layer system canbe set and, in addition, the hardness of the layer system can be furtherincreased.

As already mentioned the component AY of the second hard layer ispreferably, but not necessarily, an element of the group of the rareearths, in particular an element of the group of the chemical elementsconsisting of Y and the lanthanoids, in particular Ce and/or La whichbrings about the advantages of the layer system in accordance with theinvention as described in detail further above.

As already mentioned a component AY of the second hard layer can alsoinclude a mixed metal and it has been shown that the use of mixed metalsas a component of the chemical component AY can lead to a situation inwhich even the smallest quantities of mixed metals can enormouslyinfluence the desired properties of a layer system in accordance withthe invention without correspondingly serious changes, for example inthe chemical composition or in the lattice structure having to betolerated.

In very special cases, when for example the chemical elements which formthe component AY of the second hard layer should for specific reasonstend to have if anything a smaller atomic diameter, or when specificchemical and/or physical boundary conditions are to be satisfied, thecomponent A can be formed exclusively only of Be and/or only of Ca.

In this respect, for analogous or similar reasons or other reasonsfurther special cases are also possible. Thus the component AY of thesecond hard layer can in another case also be only Sc and/or Y and/or Laand/or AY can be only at least one element of the group of thelanthanoids, in particular only Ce and otherwise not include any otherelement.

In the following some exemplary embodiments of layer systems inaccordance with the invention with a second hard layer will be discussedand, for the sake of simplicity, only single layer systems of the secondhard layer were manufactured for the determination of specific layerparameters.

It will be understood that not only the following layer systems butrather in particular all embodiments presented in the context of thisapplication can also be advantageously combined in many ways.

In the following a second TiSiN hard layer will be discussed, which inan embodiment in accordance with the invention contains a proportion ofa cerium mixed metal. The layer was applied in a manner known per se bymeans of an arc vaporization source in a corresponding process chamberwhich is likewise known to the person skilled in the art. An arcvaporization source that is used, often simply termed a cathode, has inthe present example a diameter of 100 mm and, apart from the technicallyunimportant contaminants the following chemical composition: 82.5 at-%Ti, 17 at-% Si, 0.5 at-% cerium mixed metal (Ce_(M)), with the ceriummixed metal consisting to 54% by weight of Ce, to 29% by weight of La,to 13% by weight of Nd and to 4% by weight of Pr.

For the coating, a substrate, in the present case a high speed steel,was first heated in the process chamber to 500° C., subjected to ioncleaning and was subsequently coated at a gas pressure of approximately5 Pa, at a cathode current of ca. 130 A and at a bias voltage of ca. 50V.

For the comparison an AlTiN layer known from the prior art wasmanufactured under the same coating conditions and for which a cathodewith 55 atomic-% Al and 45 atomic-% Ti was used. The nitrogen requiredwas made available for both layers via the process gas in the processchamber.

The following Table 3 shows a comparison of the most important layercharacteristics of the two layers that are produced. In this connectionCe_(M) in Table 3 signifies a cerium mixed metal as previously defined.

TABLE 3 AlTiN TiSiCe_(M)N Micro-hardness Knoop 2226 4093 [HK0.025] Wearrate 8.09 3.59 [m²/(Nm)]

The micro-hardness in accordance with Table 3 was determined in knownmanner in accordance with the method of Knoop and the wear rate via theabrasion resistance with a KALOTEST N apparatus of the company BAQhaving a ball diameter of 30 mm and 540 shaft rotations at 60 rpm usinga grinding emulsion.

The Table 3 demonstrates in impressive manner for the TiSiCe_(M)N layerin accordance with the invention a hardness which is almost twice ashigh and a wear rate which is less than half as large in comparison tothe AlTiN layer known from the prior art.

In X-ray diffraction investigations a clearly preferred(200)-orientation of the lattice could be observed for the layers inaccordance with the invention while (111)-orientations were practicallynot observed.

As already mentioned the first hard layer can, in a preferred embodimentof a layer system in accordance with the invention, be a terminatingcover layer of the layer system, whereas in another embodiment thesecond hard layer forms a terminating cover layer of the layer system.

In the special case a layer system in accordance with the invention caninclude a functional layer, in particular a composite layer, preferablya composite layer of Met_(x)E_(y)N_(z), with x>0; y≧0 and z>0, with Metbeing at least one metal from the group Al, Cr, Mo, W, V, Nb, Ta, Ti,Zr, HF, Mn, Fe; Co; Ni, Li, Be, Mg, Sc, Y, La, Ce, Nd, Sm and E being anelement from the group Si, B, C, O.

In this connection an intermediate layer can for example be providedcomprising the elements Si and/or C and/or a gradient mixed layer isprovided which includes the elements Si and/or C of the intermediatelayer and the composition(Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k))_(α)(N_(u)C_(v)O_(w))_(β) ofthe first hard layer and/or the composition(M_(o)Si_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))_(δ) of the second hard layer.

In a special case the proportion of the metallic components of the layercan be minimized or missing altogether in the functional layer so thatSi/B dominating layers are additionally provided in a layer system inaccordance with the invention as the functional layer.

As a result of the complicated manufacture relatively little has beenknown hitherto concerning SiBx ceramics. For SiB₆ the followingparticulars are for example present for bulk materials in front of anortho-rhombic grid, hardness ca. 2600, modulus of elasticity 290 GPa,density 2.43 g/cm³, thermal coefficient expansion 4,6*10⁻⁶/° C., thermalconductivity 9 W/mK, melting point 1950° C. In particular the highoxidation resistance will be emphasized: stable in air up to 1550° C.

This stability of SiBx ceramics at high temperatures is not achieved bythe classic layer systems such as AlTiN, AlCrSiN and TiSiN. Such bulkproperties are to be found in similar form in layers of the type SiBxwith respect to the hardness and the oxidation properties, with therealization of these layers by means of PVD coating having industrialrelevance.

The mechanism of the oxidation protection of the SiBx functional layersrelates in this respect to the formation of a double layer of the typeSiO/BO. The outer Si-rich layer which arises prevents the diffusion ofoxygen into the layer.

It has thus already been proposed to use the new coating material classSiBx, and especially the new coating material class SiBCN, as a coatingmaterial for tools. In particular it has been shown that a functionallayer on the basis of SiB compounds, or of SiBNC in combination with theknown classic hard material layers likewise leads to the significantlyimproved layer characteristics, it is proposed with the presentinvention to likewise integrate such functional layers, if necessary,into a layer system of the present invention.

Depending on the requirement placed on the substrates or tools to becoated it can in a special case be advantageous to dope the functionallayers in a layer system in accordance with the invention with oxygenand thus for example to achieve SiBNCO layers, which among other thingsreduce the diffusion of oxygen by pre-oxidation or by refinement of thestructure of the layers and also massively increase the oxidationresistance at high temperatures.

The doping of the functional layer with oxygen leads moreover to anoccupation of the grain boundaries with oxygen, so that at least with apartial formation of the above-named or other double layer systems thetendency to structure conversion in the layer systems, which often havea more or less open porosity or layer defects is reduced since apre-oxidation is induced by the doping with oxygen.

In accordance with the present invention it is in this respect decisivethat the functional layers have at least the two elements Si and B, inparticular so that protective double layers can form. That is to say alayer system in accordance with the invention can have at least onefunctional layer of the composition Si_(a)B_(b)Me_(c)N_(u)C_(v)O_(w)with a,b>0 and 33 at-%>c≧0 and u,v,w≧0 with Me being a metal which, in aspecial case, can for example be a metal, for example Al or SiC, usedfor the target manufacture for the deposition of the layer in accordancewith the invention or can however be an intentionally incorporatedmetallic element.

The functional layers of a layer system in accordance with the inventioncan in this respect preferably be deposited on suitable metallicintermediate layers but also on Si, SiC intermediate layers and alsoonto a first hard layer or onto a second hard layer in accordance withthe present invention and can also be directly deposited on metallic orceramic tool materials or preferably on tool materials coated with hardmaterial layers.

Preferably, but not necessarily, the functional layers of a layer systemin accordance with the invention are present in a largely amorphousstate, wherein, in a special embodiment, a formation of nano-crystallineregions in the functional layers can be present.

The layer thicknesses of the functional layers lie in this connection inthe range between ca. 5 nm-50 000 nm, in a special case between 10 nmand 2500 nm, preferably between (100-500) nm and can as an under-layerinclude for example aluminum base hard material layers deposited in thesame or in separate plants.

The metallic component Me of a functional layer is in this respect onemetal from the group Al, Cr, Mo, W, V, Nb, Ta, Ti, Zr, HF, Mn, Fe; Co;Ni, Li, Be, Mg, Sc, Y, La, Ce, Nd, Sm.

In a particularly preferred embodiment at least one composite layer isprovided on the surface of the substrate, preferably a composite layerof Me_(x)E_(y)N_(z) with x,y≧0 and z>0, with Me being at least one metalof the group Al, Cr, Mo, W, V, Nb, Ta, Ti, Zr, HF, Mn, Fe; Co; Ni, Li,Be, Mg, Sc, Y, La, Ce, Nd, Sm and E being an element from the groupconsisting of Si, B, C, O.

For special applications a special layer system in accordance with theinvention can also be provided with an additional hard layer ofSi_(a)B_(b)Me_(c)N_(u)C_(v)O_(w), in particular an additional hard layerof Si_(a)B_(b)Me_(c)C_(v)N_(u) and especially an additional hard layerof Si_(a)B_(b)C_(v)N_(u).

In a particularly preferred embodiment an AlTi hard layer with thecomposition (Al_(1-α-β)Ti_(α)X_(β))(N_(1-γ)CO_(δ)B_(ε)) with 0,2<α<0,6,0≦β<0.2 and α+β>0.01 and 0≦γ<0.5, 0≦δ<0.5, 0≦ε<0.5 and γ+δ+ε>0.01, isprovided with X being an element of the group consisting of Zr, V, Cr,Nb, Ta; W; Mo; Hf, Mg Si, Y.

The functional layers on the basis of SiB are deposited in the range ofthe atomic composition of Si:B in the range of 9 to 0.1, with the mostdiverse compositions being presentable within a gradient layer ormulti-layer layer. Boron-rich functional layers are preferablydeposited, i.e. the Si content is smaller than the boron content. Thecomposition with 6 boron atoms per Si atom is particularly interestingsince then the particularly stable SiB6 structure can form in thefunctional layers, at least locally.

The addition of N, C; 0 leads to the formation of the most diversebonding states in the functional layers thus B—N, B—C, Si—N, Si—C, Si—O,B—O bonds arise which are however complicated and costly to quantify.The covalent bond components (for example SiN and BC) bring about a highhardness. The structural mechanism and the bonding mechanism of thesecomplex layers is not adequate with the present state of knowledge tomake predictions concerning the complex layer characteristics.

In a preferred embodiment the atomic composition of the functionallayers should consist of ca. the same proportions of Si and boron and Nand/or mixtures of N, C, O. An over-stoichiometric composition withrespect to the content of N and C related to SiB is also worthwhile,which is however problematic to manufacture technically. For example, alayer composition of this kind having ca. the same proportions of Si, Band C but ca. a proportion of N which corresponds to three times theamount of Si would be expedient in accordance with bulk ceramics.

In the above described preferred compositions of the functional layersat least local highly stable compounds can form—in the form of Si₃B₃N₇or SiBN₃C.

The oxygen contents in the functional layers are restricted tosignificantly under 50 at-%, preferably to around 10 at-% related to thetotal composition, because the ionic bonding proportion, which as a ruleleads to brittle material behavior, should be restricted.

The proportions of metals in the functional layers are likewiseexpediently set at significantly below 50 at-%, and these are mainlyrestricted to a maximum of 10 at-%-in the intermediate layers. Theseproportions thereby serve as bonding bridges to the lower hard materiallayer or originate from the target binders.

The hardnesses of the functional layers thereby cover the range of ca.1000 to 5000 Vickers, preferably between 2000 and 3500 Vickers. Theselection of suitable layers depends on the respective tribologicalproperties. By way of example, the friction is a determining factor forvarious micro-tools in order to avoid over-heating so thatfriction-reducing boron oxides are desirable with layer hardness around1000 Vickers already being expedient. A tribological partition layer isimportant. In the presence of air humidity the boron oxide is convertedto boric acid whereby low friction values can be achieved.

For ball mills (spherically shaped milling cutters) in contact with Tialloys a high hardness level should instead be set.

An intermediate layer consisting of the elements Si and/or C can beprovided not only but also to improve the bond characteristics to thesubstrate or to another layer of the layer system of the invention, forexample on a particularly heavy loaded tool.

Moreover, in a further embodiment a gradient mixed layer can be providedwhich includes the elements Si and/or C of the intermediate layer andthe composition Si_(a)B_(b)Me_(c)N_(u)C_(v)O_(w), in particularSi_(a)B_(b)Me_(c)C_(v)N_(u) and especially Si_(a)B_(b)C_(v)N_(u) of thefirst hard layer. The composition of the gradient mixed layer can inthis respect change more or less continuously from the composition of afirst layer with which the gradient mixed layer is in contact to thecomposition of a second layer with which the gradient mixed layer islikewise in contact, so that the first and the second layers, which canfor example have different chemical and/or physical properties such aslattice structure, crystallinity, thermal expansion, etc., can beideally matched to one another.

An oxygen functional layer of Si_(a)B_(b)MeN_(u)C_(v)O_(w) andespecially an Si_(a)B_(b)N_(u)C_(v)O_(w) oxygen functional layer can beparticularly advantageously provided which can in particular be providedas a cover layer. This cover layer can for example prevent or minimizethe diffusion of oxygen in the layer (but not only this) and therebyincrease the oxidation resistance amongst other things. Moreover, thecover layer can protect the layer system against external attacks, inparticular from the outside, especially by providing chemical, thermaland mechanical properties so that the layer system of the invention is,for example, particularly well protected against high temperature by thecover layer and/or has particularly advantageous mechanical propertiesor particularly good tribological properties. It will be understood thatthe previously described embodiments of the invention can also becombined in any suitable manner, depending on the application, and thatthe layer sequences which have been explained by way of example can inparticular also be realized in another manner and one or more of thelayers can be missing completely in a special embodiment of a layersystem in accordance with the invention or can also be multiply presentin another embodiment in one and the same layer system.

In a special case a layer thickness of the composite layer and/or of theintermediate layer and/or of the first hard layer and/or of the secondhard layer and/or of the gradient mixed layer can lie between 0.1 μm and50 μm, in particular between 1 μm and 15 μm and preferably between 5 μmand 8 μm.

A hardness HK 0.05 of the first hard layer and/or of the second hardlayer preferably lies between 10 GPa and 50 GPa in particular between 25GPa and 35 GPa and a residual compressive stress of the first hard layerand/or of the second hard layer lies between 0.1 GPa and 10 GPa and inparticular between 1.5 GPa and 4 GPa.

An oxidation resistance and/or a phase stability of a layer system inaccordance with the invention is in this respect guaranteed attemperatures greater than 700° C. in particular up to temperaturegreater than 1000° C.

For the application of a layer system in accordance with the inventionthe invention further relates to a first arc vaporization source havinga vaporization material as a cathode for the generation of a surfacelayer on a surface of a substrate by vaporization of the vapor materialby means of an arc discharge on a vaporization surface of the cathode.In this arrangement the vaporization material has a chemical composition(Al_(a′)Mg_(b′)Cr_(c′)Me_(d′)B_(e′)AX_(m′)Si_(k′)) with(a′+b′+c′+d′+e′+m′+k′)=100, and with Me being at least one element ofthe group of the chemical elements consisting of the secondary groupsIVb, Vb and VIb of the periodic system of the chemical elements. A is atleast one element of the group of the chemical elements consisting ofthe elements of the main groups Ia, IIa and the elements of thesecondary groups VIIb, VIIIb, Ib, IIb, IIIb and the elements of thegroup of the lanthanoids, of the periodic system of the chemicalelements, wherein 0.01≦m′<100, preferably 0.012≦m′<80. In accordancewith the invention the content of Al, Mg and Cr is restricted to 1≦a′≦97and 0.1≦b′≦20 and 30≦c′≦70.

In a special embodiment the arc vaporization source additionallycontains C and/or N and/or O and, in an embodiment which is particularlyimportant in practice, the component A can be a mixed metal.

In a special case the aluminum content lies in the range 50≦a′≦70 andthe magnesium content is restricted to a range 0.5≦b′≦10. Preferably,but not necessarily, Me is present in the arc vaporization source in aquantity corresponding to 10≦d′≦80 and the content of Si amounts at mostto k′=40 in a cathode of the present invention.

In a special case the component A is only Li and/or Be and/or Ca and/orSi, and/or A is only Sc and/or Y and/or La and in another embodiment Ais only at least one element from the group of the lanthanoids inparticular only Ce.

The invention furthermore relates to a second arc vaporization sourcewith a vaporization material as a cathode for the generation of asurface layer on a surface of a substrate by vaporization of thevaporization material by means of an arc discharge on a vaporizationsurface of the cathode, wherein the vaporization material has a chemicalcomposition (M_(k)Si_(l)A_(m)) with (k+l+m)=100, more precisely stated(M_(o′)Si_(p′)AY_(q′)) with (o′+p′+q′)=100 and wherein M is at least onemetal of the group of the chemical elements consisting of Al and theelements of the secondary groups IVb, Vb, VIb of the periodic system ofthe elements. The component A of the second arc evaporation source is atleast one element of the group of the chemical elements consisting ofMn, Fe, Co, Ni, Cu and the elements of the secondary group IIIB, and theelements of the main groups IA, IIA and IIIA, and the elements of thegroup of the lanthanoids of the periodic system of the chemicalelements.

In a preferred embodiment the second arc vaporization source canadditionally contain C and/or N and/or O and/or the component Aadditional contains boron (B).

Preferably 0.1≦p′<50 and/or the condition 0.01<q′<10 applies.

In an embodiment which is particularly important in practice thecomponent AY of the second vaporization source is a mixed metal and/orAY is an element from the group of the chemical elements consisting of Yand the lanthanoids and is in particular Ce and/or La.

In a special case the component AY of the second vaporization source canbe only Be and/or Ca and/or AY can in another embodiment be only Scand/or Y and/or La.

In a special but important case AY is only at least one element from thegroup of the lanthanoids, in particular the component AY can consistonly of Ce.

Moreover, the invention relates to a combination vaporization sourcewith a vaporization material consisting of a vaporization material ofthe first vaporization source and of the second vaporization source.

Finally the invention relates also to a substrate in particular to atool which is coated with a layer system in accordance with the presentinvention.

A tool in accordance with the invention can in this respect be anoriginal or master tool, a mould, a press tool, a chip forming tool, inparticular a drill, a milling cutter, an indexable cutting insert for aturning or milling process or a planing tool, a reshaping tool or amicro-tool, in particular a micro drill, a micro indexable cuttinginsert, a micro miller or another tool or micro tool or a plastic tool.A substrate coated in accordance with the invention can in addition be apart subjected to wear, in particular a part subjected to wear for anair or land-based turbine, for a motor, in particular for a combustionengine, especially for a seal, a gear, a piston, piston ring, a partsubjected to wear for a textile machine or another part subjected towear.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventionconcept as defined by the appended claims and their equivalents.

1-15. (canceled)
 16. A layer system for the formation of a surface layeron a surface of a substrate, comprising: at least one first layer havingthe composition(Al_(a)Mg_(b)Cr_(c)Me_(d)B_(o)AX_(m)Si_(k))_(α)(N_(u)C_(v)O_(w))_(β)with (a+b+c+d+e+m+k)=α, (u+v+w)=β, and (a+β)=100, wherein 40≦α≦60 andwherein Me is at least one metal of the group of the chemical elementsconsisting of: the elements of the secondary groups IVb, Vb, VIb of theperiodic system of elements; wherein AX is at least one element of thegroup of the chemical elements consisting of: the elements of the maingroup IA, the elements Be, Ca, Sr and Ba, the elements of the secondarygroups VIIb, VIIb, Ib, IIb and IIIb, and the elements of the group ofthe lanthanoids of the periodic system of chemical elements; wherein0.004≦m<60, 0.4≦a≦58, 0.04≦b≦12 and 18≦c≦42.
 17. The layer system ofclaim 16, wherein 0.01≦m<50.
 18. The layer system of claim 16, whereinat least one of 20≦a≦42, 0.02≦b≦6, Me is present in a quantitycorresponding to 4≦d≦54 in the hard layer, and Si is present in aquantity of at most k=24 in the hard layer.
 19. The layer system ofclaim 16, wherein AX is at least one of Li, Be, Ca and Si.
 20. The layersystem of claim 16, wherein AX is at least one of Sc, Y and La.
 21. Thelayer system of claim 16, wherein AX is at least one element of thegroup of the lanthanoids.
 22. The layer system of claim 16, wherein AXis a mixed metal.
 23. The layer system of claim 16, wherein the layersystem includes at least one additional second layer of the composition(M_(o)Si_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))_(δ) with (o+p+q)=γ, (r+s+t)=δ,and (γ+δ)=100, wherein 40≦γ≦60 and wherein M is at least one metal ofthe group of the chemical elements consisting of: Al and the elements ofthe secondary groups IVb, Vb, VIb of the periodic system of elements,wherein AY is at least one element of the group of the chemical elementsconsisting of: Mn, Fe, Co, Ni, Cu, the elements of the secondary groupIIIB, the elements of the main group IA, IIA and IIIA and the elementsof the group of the lanthanoids of the periodic system of chemicalelements.
 24. The layer system of claim 23, wherein AY further containsboron.
 25. The layer system of claim 23, wherein AY is an element of thegroup of the chemical elements consisting of Y and the lanthanoids. 26.The layer system of claim 23, wherein AY is an element of the group ofthe chemical elements consisting of Y and at least one of Ce and La. 27.The layer system of claim 23, wherein at least one of 0.04≦p≦30,0.004≦q≦6, and 0.01≦q≦10.
 28. The layer system of claim 16, wherein thefirst hard layer is a terminal cover layer of the layer system.
 29. Thelayer system of claim 23, wherein the second hard layer is a terminalcover layer of the layer system.
 30. The layer system of claim 16,further comprising a functional layer.
 31. The layer system of claim 30,wherein the functional layer is a composite layer.
 32. The layer systemof claim 30, wherein the functional layer is on a surface of thesubstrate.
 33. The layer system of claim 30, wherein the functionallayer is a composite layer of Met_(x)E_(y)N_(z), with x>0; y≧0 and z>0,wherein Met is at least one metal of the group Al, Cr, Mo, W, V, Nb, Ta,Ti, Zr, HF, Mn, Fe; Co, Ni, Li, Be, Mg, Sc, Y, La, Ce, Nd, Sm; andwherein E is an element of the group Si, B, C, O.
 34. The layer systemof claim 23, further comprising at least one of an intermediate layerand a gradient mixed layer, wherein the intermediate layer comprises atleast one of Si and C, and wherein the gradient mixed layer comprisesthe at least one of Si and C of the intermediate layer, the composition(Al_(a)Mg_(b)Cr_(c)Me_(d)B_(e)AX_(m)Si_(k))_(α)(N_(u)C_(v)O_(w))_(β) ofthe first layer, and the composition(M_(o)Si_(p)AY_(q))_(γ)(N_(r)C_(s)O_(t))_(δ) of the second layer.
 35. Anarc vaporization source having a vaporization material as cathode forthe generation of a surface layer on a surface of a substrate byvaporization of the vapor material by means of an arc discharge on avaporization surface of the cathode, wherein the vaporization materialhas a chemical composition(Al_(a′)Mg_(b′)Cr_(c′)Me_(d′)B_(e′)AX_(m′)Si_(k′)) with(a′+b′+c′+d′+e′+m′+k′)=100, wherein Me is at least one element of thegroup of the chemical elements consisting of the secondary groups IVb,Vb and VIb of the periodic system of the chemical elements, and whereinAX is at least one element of the group of the chemical elementsconsisting of the elements of the main group Ia, the elements Be, Ca,Sr, Ba, the elements of the secondary groups VIIb, VIIIb, Ib, IIb, IIIband the elements of the group of the lanthanoids of the periodic systemof the chemical elements, wherein 0.01≦m′<100, wherein 1≦a′≦97,0.1≦b′≦20 and 30≦c′≦70.
 36. The arc vaporization source of claim 35,wherein 0.012≦m′<80.
 37. The arc vaporization source of claim 35,wherein the vaporization material further comprises at least one of C, Nand O.
 38. The arc vaporization source of claim 35, wherein at least oneof 50≦a′≦70, 0.5≦b′≦10, 10≦d′≦80 and k′ is at most equal to
 40. 39. Thearc vaporization source of claim 35, wherein AX is at least one of Li,Be, Ca and Si, or wherein AX is at least one of Sc, Y and La, or whereinAX is at least one element of the group of the lanthanoids, or whereinAX is a mixed metal.
 40. An arc vaporization source having avaporization material as a cathode for the generation of a surface layeron a surface of a substrate by vaporization of the vaporization materialby means of an arc discharge on a vaporization surface of the cathode,wherein the vaporization material has a chemical composition(M_(o′)Si_(p′)AY_(q′)) with (o′+p′+q′)=100, and wherein M is at leastone metal of the group of the chemical elements consisting of Al and theelements of the secondary groups IVb, Vb, VIb of the periodic system ofthe elements and wherein AY is at least one element of the group of thechemical elements consisting of Mn, Fe, Co, Ni, Cu, the elements of thesecondary group IIIB, the elements of the main group IA, IIA and IIIAand the elements of the group of the lanthanoids of the period system ofthe chemical elements.
 41. A combination vaporization source having avaporization material in accordance with claim
 23. 42. A substratecoated with a layer system of claim 16, wherein the substrate is atleast one of an original tool, a master tool, a mould, a press tool, achip forming tool, a drill, a milling cutter, an indexable cuttinginsert, a planing tool, a reshaping tool, a micro-tool, a micro drill, amicro indexable cutting insert, a micro miller, a plastic tool, and asubstrate of a part; wherein the substrate is a part subjected to wearfrom at least one of an air-based turbine, a land-based turbine, amotor, a combustion engine, a seal, a gear, a piston, a piston ring, apart subjected to wear in a textile machine, and a part generallysubjected to wear.